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Go to Administration > Configuration > System Configuration > Advanced Configuration Options.
Click the Add button to open the Add Option dialog.
In the Name field, specify the name of the option. It has to be
pfxExternalApp_customMenuItems
.In the Value field, specify the definition of the link (see https://pricefx.atlassian.net/wiki/spaces/KB/pages/edit-v2/5566005287#Example5566005287/How+to+Add+Enable+Integration+to+the+Module+Menu#Example-of-Custom-Menu-Items-JSON-ConfigurationDefinition below).
Click Add to save changes and close the dialog.
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